When people deliberately reject Christ's offer of salvation, they reject God's most precious gift. They ignore the leading of the Holy Spirit, the one who communicates to us God's saving love.

In Hebrews 10:26-31, God's word tells us the following:

26 If we deliberately keep on sinning after we have received the knowledge of the truth, no sacrifice for sins is left, 27 but only a fearful expectation of judgment and of raging fire that will consume the enemies of God. 28 Anyone who rejected the law of Moses died without mercy on the testimony of two or three witnesses. 29 How much more severely do you think someone deserves to be punished who has trampled the Son of God underfoot, who has treated as an unholy thing the blood of the covenant that sanctified them, and who has insulted the Spirit of grace? 30 For we know him who said, “It is mine to avenge; I will repay,”and again, “The Lord will judge his people.”31 It is a dreadful thing to fall into the hands of the living God. 

What is the point here? The point is that there is no other acceptable sacrifice for our sins, but only the death of our Lord and Savior, Jesus Christ, when He took our sin debt and died on the cross for our sins. He was the sacrificial lamb that died for us. If someone deliberately rejects the sacrifice of Christ after clearly understanding the gospel and teaching about it, then there is not a way for that person to be saved, because God has not provided any other name under heaven by which we can be saved. In verse 31 says, "It is a dreadful thing to fall into the hands of the living God." This is something that nobody should want. This verse is describing the judgement for those who rejected God's mercy. For those who accept Christ's love and accept his salvation, the coming judgement is no cause to worry. Being saved through his grace, they have nothing to fear.